Curable resin composition, method for the preparation thereof, and articles derived therefrom

ABSTRACT

A curable resin composition includes an unsaturated polyester, an alkenyl aromatic compound, and a capped poly(arylene ether). The composition is suitable for low temperature curing and exhibits reduced curing shrinkage and reduced brittleness.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/176529, filed Jan. 18, 2000.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to curable resin compositions. Inparticular, the invention relates to curable resin compositionsexhibiting reduced volume change on curing.

[0003] Thermosetting resins in general, and unsaturated polyester resinsin particular, are useful in a variety of applications, includingstructural automotive parts, building and construction components, andboat hulls. In a typical sheet molding compound (SMC) formulation, theunsaturated polyester comprises only about 8 to 15% of the totalformulation. Other components include a crosslinking agent such asstyrene monomer, fillers such as calcium carbonate, glass fiber,thickeners, mold release agents, low profile additives, initiators,co-promoters, and inhibitors. Unsaturated polyester resins may exhibitexcellent physical properties and solvent resistance, as well as goodweatherability.

[0004] Notwithstanding these advantages, the commercial adoption ofunsaturated polyester resins has been limited by a number ofdeficiencies, including (1) poor surface appearance, including fiberpatterns, (2) warpage of molded parts, (3) difficulty molding to closetolerances, (4) internal cracks and voids, particularly in thicksections, and (5) notable depressions (sink marks) opposite reinforcingribs and bosses. These deficiencies are thought to be caused by the highpolymerization shrinkage from the copolymerization of the unsaturatedpolyester resin with the crosslinking agent. The shrinkage causes thecompound to pull away from the mold surface.

[0005] In a normal high-temperature-curing cycle, the liquid resin isheated to temperatures in excess of 140° C., resulting in a thermallyinduced expansion. As the unsaturated polyester resin begins tocrosslink and the unsaturated components become consumed there is anegative volume change due to the density difference. Once reaction iscomplete, the system is cooled to ambient condition, causing a furthernegative volume change. A neat polyester resin will typically exhibit asmuch as a negative 7% volume change on high-temperature curing.

[0006] Although many approaches have been taken to reduce curingshrinkage, including changes in resin and co-monomer structures, use oflarge amounts of filler, and even partial polymerization before molding,these approaches have been inadequate. Another approach has been theaddition of certain thermoplastics to the formulation. Thesethermoplastics, when functioning in such a role, are commonly referredto as low-profile additives (LPAs). Known LPAs include polymethylmethacrylates, vinyl chloride-vinyl acetate copolymers, polyurethanes,and styrene-butadiene copolymers.

[0007] The generally accepted mechanism for shrinkage control relies oninduced strain relief through stress cracking of the separate LPA phasewithin the thermoset matrix. Many known LPAs have a high molecularweight and are polar in nature to improve compatibility with the uncuredresin. During curing (crosslinking), as the resin polarity decreases,the LPA is rejected from the matrix and isolated as solid domains,typically less than about 5 micrometers in size. These distinct LPAdomains dispersed in the cured thermoset matrix act as strain reliefsites. Thus when the strain increases it can induce preferential stresscracking through the weak thermoplastic phase, thus relieving thestrain, forming voids and compensating for the overall shrinkage.

[0008] However, in low temperature curing applications, known LPAs arenot as effective. Thus, there is a need for a shrinkage control andstress release agent for low-temperature curing applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is an image of molded unsaturated polyester resin (UPR)with no low-profile additive (#3), with polyvinyl acetate (#1), and witha capped poly(arylene ether) (#2). See Examples 1-6 and ComparativeExamples 1-6.

[0010]FIG. 2 is an image of molded UPR compositions comprising, fromlower right to upper left, 0, 2, 4, and 6 weight percent cappedpoly(arylene ether). See Examples 8-13 and Comparative Example 11.

[0011]FIG. 3 is an image of parts molded from a composition comprisingan unsaturated polyester, a capped poly(arylene ether), and varyinglevels of curing catalyst and curing promoter. See Examples 14-21.

BRIEF SUMMARY OF THE INVENTION

[0012] The above-described and other drawbacks and disadvantages of theprior art are alleviated by a curable resin composition, comprising:

[0013] an unsaturated polyester;

[0014] an alkenyl aromatic monomer; and

[0015] an amount of a capped poly(arylene ether) effective to reducecuring shrinkage.

[0016] The present inventors have found capped poly(arylene ether)s aremore effective at reducing shrinkage and relieving stress thancommercially available LPAs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A curable resin composition comprises:

[0018] an unsaturated polyester;

[0019] an alkenyl aromatic monomer; and

[0020] an amount of a capped poly(arylene ether) effective to reducecuring shrinkage.

[0021] The composition comprises an unsaturated polyester. Anunsaturated polyester is generally obtained by reaction of at least onepolyhydric alcohol with at least one polybasic acid comprising anunsaturated polybasic acid.

[0022] Specific examples of unsaturated polybasic acids that may be usedto form the unsaturated polyester include maleic anhydride, maleic acid,fumaric acid, itaconic acid, citraconic acid, chloromaleic acid, dimericmethacrylic acid, nadic acid, tetrahydrophthalic acid,endo-methylenetetrahydrophthalic acid,hexachloro-endo-methylenetetrahydrophthalic acid, halogenated phthalicacids, and the like, as well as their corresponding acids, esters, andanhydrides. Preferred unsaturated acids include maleic acid, fumaricacid, and their esters and anhydrides.

[0023] Often, polyfunctional saturated and aromatic acids are employedin conjunction with the polybasic unsaturated acids to reduce thedensity of the ethylenic unsaturation and provide the desired chemicaland mechanical properties to the coating. Examples of saturated andaromatic polybasic acids include succinic acid, adipic acid, sebacicacid, azelaic acid, dodecanedioic acid, eicoic acid, phthalic acid,isophthalic acid, terephthalic acid, and the like, as well as theiresters and anhydrides. Preferred aromatic polybasic acids includephthalic acid, isophthalic acid, and their esters and anhydrides.

[0024] Examples of polyhydric alcohols include ethylene glycol,propylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, neopentyl glycol, glycerol, triethyleneglycol, pentanediol, hexylene glycol, hydrogenated bisphenol A,bisphenol A-alkylene oxide adducts, tetrabromobisphenol A-alkylene oxideadducts, and the like. Preferred polyhydric alcohols include propyleneglycol.

[0025] Unsaturated polyesters are commercially available, often ascompositions further comprising an alkenyl aromatic monomer, andinclude, for example, the unsaturated polyester resins obtained fromAshland as Ashland Q6585, and from Alpha Owens Corning as AOC-XV2346.

[0026] The composition may comprise the unsaturated polyester in anamount of about 20 to about 80 parts, preferably about 30 to about 75parts, more preferably about 40 to about 70 parts, per 100 parts resin.Unless otherwise specified, all parts are parts by weight.

[0027] In addition to the unsaturated polyester, the composition furthercomprising an alkenyl aromatic monomer. The alkenyl aromatic monomer mayhave the structure

[0028] wherein each R¹ may be hydrogen, C₁-C₁₂ alkyl, or the like; eachR² may be halogen, C₁-C₁₂ alkyl, C₁-C₁₂ alkoxyl, or the like; X isnitrogen or carbon; p is 1 to 4; and q is 0 to 5. When p=l, the alkenylaromatic monomer is termed a monofunctional alkenyl aromatic monomer;when p=2-4, the alkenyl aromatic monomer is termed a polyfunctionalalkenyl aromatic monomer. Suitable alkenyl aromatic monomers includestyrene, alpha-methylstyrene, alpha-ethylstyrene,alpha-isopropylstyrene, alpha-tertiary-butylstyrene,alpha-phenylstyrene, and the like; halogenated styrenes such aschlorostyrene, dichlorostyrene, trichlorostyrene, bromostyrene,dibromostyrene, tribromostyrene, fluorostyrene, difluorostyrene,trifluorostyrene, tetrafluorostyrene, pentafluorostyrene, and the like;halogenated alkylstyrenes such as chloromethylstyrene, and the like;alkoxystyrenes such as methoxystyrene, ethoxystyrene,1,3-divinylbenzene, 1,4-divinylbenzene, trivinylbenzene,1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, and the like;vinylpyridine, 2,4-divinylpyridine, 2,5-divinylpyridine,2,6-divinylpyridine, 3,5-divinylpyridine, 2,4,6-trivinylpyridine, andthe like; and mixtures comprising at least one of the foregoing alkenylaromatic monomers. In the foregoing substituted styrenes for which nosubstituent position is specified, the substituent may occupy any freeposition on the aromatic ring.

[0029] Preferred alkenyl aromatic monomers include styrene,alpha-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene,2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene,1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-diisopropenylbenzene,1,4-diisopropenylbenzene, and the like, and mixtures comprising at leastone of the foregoing alkenyl aromatic monomers. Preferred alkenylaromatic monomers further include styrenes having from 1 to 5 halogensubstituents on the aromatic ring, and mixtures comprising at least onesuch halogenated styrene.

[0030] The composition may comprise the alkenyl aromatic monomer in anamount of about 10 to about 70 parts, preferably about 20 to about 60parts, more preferably about 30 to about 60 parts, per 100 parts resin.

[0031] In addition to the unsaturated polyester and the alkenyl aromaticmonomer, the curable resin composition comprises a capped poly(aryleneether). A capped poly(arylene ether), is defined herein as apoly(arylene ether) in which at least 10%, preferably at least 50%, morepreferably at least 75%, yet more preferably at least 90%, even morepreferably at least 95%, of the free hydroxyl groups present in thecorresponding uncapped poly(arylene ether) have been removed by reactionwith a capping agent.

[0032] There is no particular limitation on the intrinsic viscosity ofthe capped poly(arylene ether). The poly(arylene ether) may have anintrinsic viscosity of about 0.05 to about 0.80, as measured inchloroform at 23° C. In a preferred embodiment, the intrinsic viscositymay be about 0.08 to about 0.40 deciliters per gram (dl/g), preferablyabout 0.10 to about 0.35 dl/g, more preferably about 0.12 to about 0.31dl/g. Generally, the intrinsic viscosity of the capped poly(aryleneether) will vary insignificantly from the intrinsic viscosity of thecorresponding uncapped poly(arylene ether). It is expressly contemplatedto employ blends of at least two capped poly(arylene ether)s havingdifferent molecular weights and intrinsic viscosities.

[0033] The capped poly(arylene ether) may be represented by thestructure

Q—(J—K)_(y)

[0034] wherein Q is the residuum of a monohydric, dihydric, orpolyhydric phenol, preferably the residuum of a monohydric or dihydricphenol, more preferably the residuum of a monohydric phenol; y is 1 to100; J comprises recurring units having the structure

[0035] wherein R³-R⁶ may be hydrogen, halogen, primary or secondaryC₁-C₁₂ alkyl, C₁-C₁₂ alkenyl, C₁-C₁₂ alkynyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂hydroxyalkyl, phenyl, C₁-C₁₂ haloalkyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂hydrocarbonoxy, C₁-C₁₂ halohydrocarbonoxy wherein at least two carbonatoms separate the halogen and oxygen atoms, or the like; m is 1 toabout 200; and K is a capping group produced by reaction of the phenolichydroxyl groups on the poly(arylene ether) with a capping reagent. Theresulting capping group may be selected from the group consisting of

[0036] wherein R⁷ may be C₁-C₁₂ alkyl, or the like; R⁸-R¹⁰ may behydrogen, C₁-C₁₂ alkyl, C₁-C₁₂ alkenyl, C₁-C₁₂ aryl, C₁-C₁₂ mixed(alkyl-aryl), C₁-C₁₂ alkoxycarbonyl, C₁-C₁₂ aryloxycarbonyl, mixed(alkyl-aryl)oxycarbonyl, nitrile, formyl, carboxylate, imidate,thiocarboxylate, or the like; R¹¹-R¹⁵ may be hydrogen, halogen, C₁-C₁₂alkyl, hydroxy, amino, or the like; and wherein Y is a divalent groupselected from the group consisting of

[0037] wherein R¹⁶ and R¹⁷ may be hydrogen, C₁-C₁₂ alkyl, or the like.

[0038] In one embodiment, Q is the residuum of a phenol, includingpolyfunctional phenols, and includes radicals of the structure

[0039] wherein R³-R⁶ may be hydrogen, halogen, primary or secondaryC₁-C₁₂ alkyl, C₁-C₁₂ alkenyl, C₁-C₁₂ alkynyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂hydroxyalkyl, phenyl, C₁-C₁₂ haloalkyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂hydrocarbonoxy, C₁-C₁₂ halohydrocarbonoxy wherein at least two carbonatoms separate the halogen and oxygen atoms, or the like; Z may behydrogen, C₁₋₂₀ alkyl, aryl, mixed alkyl-aryl hydrocarbons, suchhydrocarbon groups containing a substituent selected from the groupconsisting of carboxylic acid, aldehyde, alcohol, and amino radicals, orthe like; Z also may be sulfur, sulfonyl, sulfuryl, oxygen, or othersuch bridging group having a valence of 2 or greater to result invarious bis- or higher polyphenols; n is 1 to about 100, preferably 1 to3, and most preferably 1 or 2.

[0040] In one embodiment, the capped poly(arylene ether) is produced bycapping an uncapped poly(arylene ether) consisting essentially of thepolymerization product of at least one monohydric phenol having thestructure

[0041] wherein R³-R⁶ may be hydrogen, halogen, primary or secondaryC₁-C₁₂ alkyl, C₁-C₁₂ alkenyl, C₁-C₁₂ alkynyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂hydroxyalkyl, phenyl, C₁-C₁₂ haloalkyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂hydrocarbonoxy, C₁-C₁₂ halohydrocarbonoxy wherein at least two carbonatoms separate the halogen and oxygen atoms, or the like. Suitablemonohydric phenols include those described in U.S. Pat. No. 3,306,875 toHay, and highly preferred monohydric phenols include 2,6-dimethylphenoland 2,3,6-trimethylphenol.

[0042] In a preferred embodiment, the capped poly(arylene ether)comprises at least one capping group having the structure

[0043] wherein R⁸-R¹⁰ may be hydrogen, C₁-C₁₂ alkyl, C₁-C₁₂ alkenyl,C₁-C₁₂ aryl, C₁-C₁₂ mixed (alkyl-aryl), C₁-C₁₂ alkoxycarbonyl, C₁-C₁₂aryloxycarbonyl, mixed (alkyl-aryl)oxycarbonyl, nitrile, formyl,carboxylate, imidate, thiocarboxylate, or the like. Highly preferredcapping groups include acrylate (R⁸=R⁹=R¹⁰=hydrogen) and methacrylate(R⁸=methyl, R⁹=R¹⁰=hydrogen).

[0044] In another preferred embodiment, the capped poly(arylene ether)comprises at least one capping group having the structure

[0045] wherein R⁷ is C₁-C₁₂ alkyl, preferably C₁-C₆ alkyl, morepreferably methyl or isopropyl.

[0046] In yet another preferred embodiment, the capped poly(aryleneether) comprises at least one capping group having the structure

[0047] wherein R¹¹-R¹⁵ may be hydrogen, halogen, C₁-C₁₂ alkyl, hydroxy,amino, or the like. Preferred capping groups of this type includesalicylate (R⁹=hydroxy, R¹⁰-R¹³=hydrogen).

[0048] In a preferred embodiment, the capped poly(arylene ether) issubstantially free of amino substituents, including alkylamino anddialkylamino substituents, wherein substantially free means that thecapped poly(arylene ether) contains less than about 300 micrograms,preferably less than about 100 micrograms, of atomic nitrogen per gramof capped poly(arylene ether). Although many poly(arylene ether)s aresynthesized by processes that result in the incorporation of aminosubstituents, the present inventors have found that thermoset curingrates are increased when the capped poly(arylene ether) is substantiallyfree of amino substituents. Poly(arylene ether)s substantially free ofamino substituents may be synthesized directly or generated by heatingamino-substituted poly(arylene ether)s to at least about 200° C.

[0049] There is no particular limitation on the method by which thecapped poly(arylene ether) is prepared. The capped poly(arylene ether)may be formed by the reaction of an uncapped poly(arylene ether) with acapping agent. Capping agents include compounds known in the literatureto react with phenolic groups. Such compounds include both monomers andpolymers containing, for example, anhydride, acid chloride, epoxy,carbonate, ester, isocyanate, cyanate ester, or alkyl halide radicals.Capping agents are not limited to organic compounds as, for example,phosphorus and sulfur based capping agents also are included. Examplesof capping agents include, for example, acetic anhydride, salicylicanhydride, polyesters comprising salicylate units, homopolyesters ofsalicylic acid, acrylic anhydride, methacrylic anhydride, glycidylacrylate, glycidyl methacrylate, acetyl chloride, benzoyl chloride,diphenyl carbonates such as di(4-nitrophenyl)carbonate, acryloyl esters,methacryloyl esters, acetyl esters, phenylisocyanate,3-isopropenyl-alpha,alpha-dimethylphenylisocyanate, cyanatobenzene,2,2-bis(4-cyanatophenyl)propane), 3-(alpha-chloromethyl)styrene,4-(alpha-chloromethyl)styrene, allyl bromide, and the like, carbonateand substituted derivatives thereof, and mixtures thereof. These andother methods of forming capped poly(arylene ether)s are described, forexample, in U.S. Pat. No. 3,375,228 to Holoch et al.; U.S. Pat. No.4,148,843 to Goossens; U.S. Pat. Nos. 4,562,243, 4,663,402, 4,665,137,and 5,091,480 to Percec et al.; U.S. Pat. Nos. 5,071,922, 5,079,268,5,304,600, and 5,310,820 to Nelissen et al.; U.S. Pat. No. 5,338,796 toVianello et al.; and European Patent No. 261,574 B1 to Peters et al.

[0050] In a preferred embodiment, the capped poly(arylene ether) may beprepared by reaction of an uncapped poly(arylene ether) with ananhydride in the alkenyl aromatic monomer as solvent. This approach hasthe advantage of generating the capped poly(arylene ether) in a formthat can be immediately blended with other components to form a curablecomposition; using this method, no isolation of the capped poly(aryleneether) or removal of unwanted solvents or reagents is required.

[0051] A capping catalyst may be employed in the reaction of an uncappedpoly(arylene ether) with an anhydride. Examples of such compoundsinclude those known to the art that are capable of catalyzingcondensation of phenols with the capping agents described below. Usefulmaterials are basic compounds including, for example, basic compoundhydroxide salts such as sodium hydroxide, potassium hydroxide,tetraalkylammonium hydroxides, and the like; tertiary alkyl amines suchas tributyl amine, triethylamine, dimethylbenzylamine,dimethylbutylamine and the like; tertiary mixed alkyl-arylamines andsubstituted derivatives thereof such as dimethylaniline, and the like;heterocyclic amines such as imidazoles, pyridines, and substitutedderivatives thereof such as 2-methylimidazole, 2-vinylimidazole,4-(dimethylamino)pyridine, 4-(pyrrolino)pyridine, 2-, 3-, or4-vinylpyridine. Also useful are organometallic salts such as, forexample, tin and zinc salts known to catalyze the condensation of, forexample, isocyanates or cyanate esters with phenols. The organometallicsalts useful in this regard are known to the art in numerouspublications and patents well known to those skilled in this art.

[0052] The composition may comprise a blend of at least two cappedpoly(arylene ether)s. Such blends may be prepared from individuallyprepared and isolated capped poly(arylene ether)s. Alternatively, suchblends may be prepared by reacting a single poly(arylene ether) with atleast two capping agents.

[0053] The capped poly(arylene ether) may be used an any amounteffective to reduce the curing shrinkage of the composition compared tothe curing shrinkage of the corresponding composition without the cappedpolyarylene ether.

[0054] The curing shrinkage of a cured object comprising the compositionmay be defined by the equation$S = {100( \frac{L_{before} - L_{after}}{L_{before}} )}$

[0055] wherein S is the curing shrinkage expressed as a percent,L_(before) is the length before curing of a molded object comprising thecomposition, and L_(after) is the length after curing of a molded objectcomprising the composition. In a preferred embodiment, the cappedpoly(arylene ether) is used in an amount effective to produce shrinkagein any one dimension not greater than about 3%, preferably not greaterthan about 2%, more preferably not greater than about 1%. In some casesthe addition of the capped poly(arylene ether) may result in expansionafter curing, which leads to a negative value of S. In such cases, it ispreferred that the curing shrinkage not be less than about −3%, morepreferably not less than about −2%, yet more preferably not less thanabout −1%.

[0056] Shrinkage of the composition may be expressed relative to theshrinkage of the corresponding composition without the cappedpoly(arylene ether). Thus, shrinkage reduction may be defined by theequation${SR} = {100{\frac{S_{- {cappedPPE}} - S_{+ {cappedPPE}}}{S_{- {cappedPPE}}}}}$

[0057] where SR is the shrinkage reduction expressed as a percentage,S_(+cappedPPE) is the curing shrinkage, as defined above, of a moldedobject comprising the composition with the capped poly(arylene ether),and S_(−cappedPPE) is the curing shrinkage of a molded object comprisingthe corresponding composition without the capped poly(arylene ether). Itis preferred that the capped poly(arylene ether) be used in an amounteffective to produce a shrinkage reduction of at least about 25%,preferably at least about 50%, more preferably at least about 75%. Inthe instances in which the composition without capped poly(aryleneether) exhibits curing shrinkage and the composition with cappedpoly(arylene ether) exhibits curing expansion, the value of SR willexceed 100%. As it may sometimes be desirable for the composition toexhibit slight expansion on curing, it is preferred that the cappedpoly(arylene ether) be used in an amount effective to produce ashrinkage reduction not greater than about 150%, more preferably notgreater than about 125%, yet more preferably not greater than about110%.

[0058] The effective amount of the capped poly(arylene ether) willdepend on the nature and amount of the unsaturated polyester, the natureand amount of the alkenyl aromatic monomer, and the nature of the cappedpoly(arylene ether), as well as the curing conditions. Generally, thecomposition may comprise the capped poly(arylene ether) in an amount ofabout 0.1 to about 12 parts, preferably about 0.5 to about 10 parts,more preferably about 1 to about 8 parts, per 100 parts resin.

[0059] In addition to the components discussed above, the curable resincomposition may, optionally, further comprise a curing catalyst. Curingcatalysts, also referred to as initiators, are well known to the art andused to initiate the polymerization, cure or crosslink any of numerousthermoplastics and thermosets including unsaturated polyester, vinylester and allylic thermosets. Non-limiting examples of curing catalystsare those described in “Plastic Additives Handbook, 4^(th) Edition” R.Gachter and H. Muller (eds.), P. P. Klemchuck (assoc. ed.) HansenPublishers, New York 1993 and in U.S. Pat. No. 5,407,972 to Smith etal., and U.S. Pat. No. 5,218,030 to Katayose et al. The curing catalystfor the unsaturated portion of the thermoset may include any compoundcapable of producing radicals. Such curing catalysts may include bothperoxy and non-peroxy based radical initiators. Examples of peroxyinitiators useful in the present invention include, for example, benzoylperoxide, dicumyl peroxide, methyl ethyl ketone peroxide, laurylperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl benzenehydroperoxide, t-butyl peroctoate,2,5-dimethylhexane-2,5-dihydroperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide,t-butylcumyl peroxide,alpha,alpha′-bis(t-butylperoxy-m-isopropyl)benzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumylperoxide,di(t-butylperoxy isophthalate, t-butylperoxybenzoate,2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide,trimethylsilylphenyltriphenylsilyl peroxide, and the like, and mixturescomprising at least one of the foregoing curing agents. Typicalnon-peroxy initiators include, for example,2,3-dimethyl-2,3-diphenylbutane,2,3-trimethylsilyloxy-2,3-diphenylbutane, and the like, and mixturescomprising at least one of the foregoing curing catalysts.

[0060] In a preferred embodiment, the curing catalyst may compriset-butyl peroxybenzoate and/or methyl ethyl ketone peroxide. The curingcatalyst will preferably promote curing at a temperature of about 0° C.to about 200° C., preferably about 20° C. to about 50° C., morepreferably about 25° C. to about 40° C.

[0061] When present, the curing catalyst may be used in an amount ofabout 0.1 to about 10 parts, preferably about 0.2 to about 5 parts, morepreferably about 0.5 to about 2 parts, per 100 parts resin.

[0062] The composition may, optionally, further comprise a curingpromoter to decrease the gel time. Suitable curing promoters includetransition metal salts and complexes such as cobalt naphthanate andcobalt ethylhexanoate; and organic bases such as N,N-dimethylaniline(DMA) and N,N-diethylaniline (DEA). In one embodiment, cobaltnaphthanate and DMA are used in combination. When present, the curingpromoter may be used in an amount of about 0.01 to about 1 parts,preferably about 0.02 to about 0.5 parts, more preferably about 0.05 toabout 0.2 parts, per 100 parts resin.

[0063] When the composition is to be cured using ultraviolet light, itmay further comprise a photoinitiator, such as, for example, thephotoinitiators described in U.S. Pat. No. 5,407,972, including, forexample, ethyl benzoin ether, isopropyl benzoinether, butyl benzoinether, isobutyl benzoin ether, alpha,alpha-diethoxyacetophenone,alpha,alpha-dimethoxy-alpha-phenylacetophenone,diethoxyphenylacetophenone, 4,4′-dicarboethoxybenzoin ethylether,benzoin phenyl ether, alpha-methylbenzoin ethyl etheralpha-methylolbenzoin methyl ether, trichloroacetophenone, and the like,and mixtures comprising at least one of the foregoing photoinitiators.

[0064] The composition may further comprise additives known in the art,including, for example, flame retardants, flame retardant synergists,mold release agents and other lubricants, antioxidants, thermalstabilizers, ultraviolet stabilizers, pigments, dyes, colorants,anti-static agents, fibrous reinforcements, disc-shaped fillers,low-aspect ratio fillers, synthetic and/or natural resins includingthermoplastic elastomers, additional low profile additives, and thelike.

[0065] Flame retardant compounds include those known to the art asdescribed in numerous publications and patents known to those skilled inthis art. Useful in formulating flame retardant compositions are, forexample, brominated flame retardant compounds. Preferred brominatedflame retardant compounds include, for example,1,3,5-tris(2,4,6-tribromophenoxy)triazine, polybrominated diphenylethers, poly(2,6-dibromophenylene ether), brominated polystyrene,brominated cyclododecane, brominated bisphenol-A diglycidyl ether,hydroxyethyl ether, C₁₋₁₀₀ aromatic or mixed aromatic-aliphaticphosphate esters such as triphenyl, tricresyl phosphate,tris(2-allylphenylphosphate), tris(2-methoxy-4-allylphosphate),tris(2-propenylphenyl)phosphate, tris(4-vinylphenyl)phosphatebis(diphenylphosphate ester)s of bisphenols such as bisphenol-A,resorcinol or hydroquinone or the bis(diphenyl phosphoramide)s ofdiamines such as 1,6-hexanediamine or piperidine, and alkylated orsubstituted derivatives therefrom. If brominated flame retardants areused, it is preferred that the bromine content of the brominated flameretardant be greater than 45%, advantageously greater than 60%, andpreferably greater than 70%. The high bromine content of the flameretardant allows one to obtain UL-94 flammability and at the same timemaintaining high poly(arylene ether) content and optimal dielectricproperties.

[0066] Useful fillers and reinforcements include those known to the artknown to augment or modify the properties of plastics. Examples of suchfillers well known to the art include those described in “PlasticAdditives Handbook, 4^(th) Edition” R. Gachter and H. Muller (eds.), P.P. Klemchuck (assoc. ed.) Hansen Publishers, New York 1993. Non-limitingexamples of fillers include silica powder, such as fused silica andcrystalline silica; boron-nitride powder and boron-silicate powders forobtaining cured products having low dielectric constant and lowdielectric loss tangent; the above-mentioned powder as well as alumina,and magnesium oxide (or magnesia) for high temperature conductivity; andfillers, such as wollastonite including surface-treated wollastonite,calcium sulfate (as its anhydride, dihydrate or trihydrate), calciumcarbonate including chalk, limestone, marble and synthetic, precipitatedcalcium carbonates, generally in the form of a ground particulate whichoften comprises 98+weight % CaCO₃ with the remainder being otherinorganics such as magnesium carbonate, iron oxide andalumino-silicates; surface-treated calcium carbonates; talc, includingfibrous, modular, needle shaped, or, preferably, lamellar talc; glassspheres, both hollow and solid, and surface-treated glass spherestypically having coupling agents such as silane coupling agents and/orcontaining a conductive coating; and kaolin, including hard, soft,calcined kaolin, and kaolin comprising various coatings known to the artto facilitate the dispersion in and compatibility with the thermosetresin; mica, including metallized mica and mica surface treated withaminosilanes or acryloylsilanes coatings to impart good physicals tocompounded blends; feldspar and nepheline syenite; silicate spheres;flue dust; cenospheres; finite; aluminosilicate (atmospheres), includingsilanized and metallized aluminosilicate; natural silica sand, quartz;quartzite; perlite; Tripoli; diatomaceous earth; synthetic silica,including those with various silane coatings, and the like.

[0067] The above fillers may be used in metallized or silane coatedforms to improve compatibility and adhesion with the thermoset blend.

[0068] Other mineral fillers include silicon carbide to increase theabrasive action of polymers; molybdenum sulfide to improve thelubricity, zinc sulfide to impart a white coloration; aluminum silicate(mullite), synthetic calcium silicate and zirconium silicate to improveslip properties; barium titanate to enhance dielectric properties;barium ferrite to produce magnetized polymers; and barium sulfate andheavy spar.

[0069] Fillers also include metals and metal oxides, includingparticulate or fibrous aluminum, bronze, zinc, copper, and nickel toimprove, for example, thermal, electrical conductivity or resistance toneutron or gamma rays. Aluminum hydroxide may be incorporated to improvethe flammability of a polymer resin.

[0070] Fillers also include carbon, such as carbon black for use as apotential colorant or to achieve improved volume conductivity(conductive carbon black) and heat deflection temperature. Graphite,such as graphite powder may be used to impart lubricity and/orconductivity to the formulation.

[0071] Fillers also include flaked fillers and reinforcements, such asglass flakes, flaked silicon carbide, aluminum diboride, aluminumflakes, and steel flakes.

[0072] Fillers also include short inorganic fibers, including processedmineral fibers such as those derived from blends comprising at least oneof aluminum silicates, aluminum oxides, magnesium oxides, and calciumsulfate hemihydrate.

[0073] Fillers also include natural fillers and reinforcements, such aswood flour obtained by pulverizing wood, and fibrous products such ascellulose, cotton, sisal, jute, starch, cork flour, lignin, ground nutshells, corn, rice grain husks.

[0074] Fillers also include synthetic reinforcing fibers includingpolyesters such as polyethylene terephthalate, polyvinylalcohol; andhigh tenacity fibers with high thermal stability, including basaltfibers, carbon fibers, aromatic polyamide fibers, polybenzimidazole,also polyimide fibers such as polyimide 2080 and PBZ fiber (bothproducts of Dow Chemical Company, Midland, Mich. USA). polyphenylenesulfide fiber, polyether ether ketone, boron fibers, ceramic fibers suchas silicon carbide, and fibers from mixed oxides of aluminum, boron andsilicon sold under the trade name “Nextel” by 3M Co., St. Paul, Minn.,USA.

[0075] Fillers also include single crystal fibers or “whiskers”,including silicon carbide, alumina, boron carbide, carbon, iron, nickel,and copper.

[0076] Fillers also include electrically conductive polymers, such aspolypyrrole, polyaniline, polyphenylene, polyacetylene, and substitutedderivatives there of, including derivatives substituted with C₁-C₂₅alkyl, C₁-C₂₅ alkoxy, C₁-C₂₅ alkylcarbonyl, C₁-C₂₅ alkylcarbonyloxy,C₆-C₂₅ aryl, C₆-C₂₅ aryloxy, C₆-C₂₅ arylcarbonyl, and C₆-C₂₅arylcarbonyloxy.

[0077] Fillers also include fibers, including textile glass fibers suchas E, A, C, ECR, R, S, D, and NE glasses and quartz.

[0078] These aforementioned fillers may be added to the thermosettingresin without any treatment, or after surface treatment, generally withan adhesion promoter.

[0079] The formulation may also contain adhesion promoters to improveadhesion of the thermosetting resin to the filler or to an externalcoating or substrate. Also possible is treatment of the aforementionedinorganic fillers may be treated with and adhesion promoter to improveadhesion. Adhesion promoters include chromium complexes, silanes,titanates, zirco-aluminates, propylene maleic anhydride copolymers,reactive cellulose esters and the like. Chromium complexes include thoseonce sold under the tradename VOLAN® are included. Silanes includemolecules having the general structure (RO)_((4−n))SiY_(n) whereinn=1-3, R is an alkyl or aryl group and Y is a reactive functional groupwhich can enable formation of a bond with a polymer molecule.Particularly useful examples of coupling agents are those having thestructure (RO)₃SiY. Typical examples include vinyl-triethoxysilane,vinyl tris(2-methoxy)silane, g-methacryloxypropyltrimethoxy silane,g-aminopropyltriethoxysilane, g-glycidoxypropyltrimethoxysilane,g-mercaptopropyltrimethoxysilane. Titanates include those developed byS. J. Monte et al. in Ann. Chem. Tech Conf. SPI (1980), Ann. Tech Conf.Reinforced Plastics and Composite inst. SP1 1979, Section 16E, NewOrleans; and S. J. Monte, Mod. Plastics Int., volume 14 (1984), no. 6.pg. 2. Zirco-aluminates include those described by L. B. Cohen inPlastics Engineering, volume 39, (1983), no. 11, pg. 29. The adhesionpromoter may be included in the thermosetting resin itself, or coatedonto any of the fillers described above to improve adhesion between thefiller and the thermosetting resin. For example such promoters may beused to coat a silicate fiber or filler to improve adhesion of the resinmatrix.

[0080] Fillers may also include lubricants such as fatty alcohols andtheir dicarboxylic acid esters including cetyl, stearyl and tall oilalcohol, distearyl adipate, distearyl phthalate, fatty acid esters ofglycerol and other short chain alcohols including glycerol monooleate,glycerol monostearate, glycerol 12-hydroxystearate, glyceroltristearate, trimethylol propane tristearate, pentaerythritoltetrastearate, butyl stearate, isobutyl stearate, stearic acids,12-hydroxystearic acid, oleic acid amide, erucamide,bis(stearoyl)ethylene diamine, calcium stearate, zinc stearate, neutrallead stearate, dibasic lead stearate, stearic acid complex esters, oleicacid complex esters, calcium soap containing complex esters, fattyalcohol fatty acid esters including isotridecyl stearate, cetylpalmitate, stearyl stearate, behenyl behenate, montanic acid, montanicacid ethylene glycol esters, montanic acid glycerol esters, montanicacid pentaerythritol esters, calcium soap containing montanic acidesters, calcium montanate, sodium montanate; linear or branchedpolyethylene, partially saponified polyethylene wax, ethylene-vinylacetate copolymer, crystalline polyethylene wax; natural or syntheticparaffin including fully refined wax, hardened paraffin wax, syntheticparaffin wax, microwax, and liquid paraffin; fluoropolymers includingpolytetrafluoroethylene wax, copolymers with vinylidene fluoride, andmixtures comprising at least one of the foregoing lubricants.

[0081] Fillers may also include buckminsterfullerenes, conductive carbonfibers, vapor-grown carbon fibers, nanotubes, aerogels and xerogels.Preferred vapor-grown carbon fibers include those having an averagediameter of about 3.5 to about 500 nanometers as described in, forexample, U.S. Pat. Nos. 4,565,684 and 5,024,818 to Tibbetts et al.; U.S.Pat. No. 4,572,813 to Arakawa; U.S. Pat. Nos. 4,663,230 and 5,165,909 toTennent; U.S. Pat. No. 4,816,289 to Komatsu et al.; U.S. Pat. No.4,876,078 to Arakawa et al.; U.S. Pat. No. 5,589,152 to Tennent et al.;and U.S. Pat. No. 5,591,382 to Nahass et al.

[0082] Organic fillers such as thermoplastics and rubbers or elastomersmay also be used. Examples of thermoplastics include powdery engineeringresins, such as polycarbonate, thermoplastic polyester,polyestercarbonate, polyphenylene ether, polysulfone, polyether sulfone,and polyacrylate; powdery polyolefins, such as polyethylene,polypropylene and poly-4-methyl pentene-1; fluoroplastics, such aspolytetrafluoroethylene, tetrafluoroethylene-propylene copolymer;chlorinated polyethylene; ethylene vinylacatate copolymers;polyacrlyates such as polybutyl acrylate, poly(2-hexyl acrylate);core-shell impact modifiers, such aspolymethylmethacrylate-polybutylacrylate,poly(acrylonitrile-butadiene-styrene), poly(styrene-acrylonitrile)copolymers, poly(methylmethacrylate-butadiene-styrene) terpolymers;polyphenylene ether; ethylene propylene rubbers including diene modifiedethylene propylene rubbers, and butadiene/styrene block copolymers.

[0083] Fillers may also include organic fillers such as rubbers,including acrylate-butadiene rubber, copolymers of ethyl acrylate (orother acrylates) and a small amount of a monomer that facilitatesvulcanization (acrylic rubber), terpolymer from tetrafluoroethylene,trifluoronitrosomethane, and nitroso-perfluorobutyric acid (nitrosorubber), ethylacrylate-acrylonitrile copolymer (acrylate rubber),alkylene sulfide rubber, urethane rubber based on polyester, butadienerubber (polybutadiene), bromobutyl rubber, chlorobutyl rubber,polychlorotrifluoroethylene (fluoro rubber), chloropolyethylene,epichlorohydrin homopolymer rubber (polychloromethytoxiran), chloroprenerubber (polychloroprene), chlorosulfonylpolyethylene, ethylene-ethylacrylate copolymer (e.g., VAMAC®), copolymer of ethylene oxide (oxiran)and chloromethyloxiran (epichlorohydrin rubber), epoxidized naturalrubber, ethylene-propylene-diene terpolymer, ethylene-propylenecopolymer, urethane rubber based on polyether,epichlorohydrin-ethyleneoxide terpolymer, ethylene-vinylacetatecopolymer, methyl silicone rubber with fluoro groups, rubber havingfluoro or fluoroalkyl or fluoroalkoxy substituent groups on the polymerchain, copolymer from propylene oxide and allyl glycidyl ether,hydrogenated nitrile rubber, isobutylene-isoprene rubber (butyl rubber),polyisobutene, synthetic isoprene rubber, liquid silicone rubber, methylsilicone rubber, acrylonitrile-butadiene rubber,acrylonitrile-chloroprene rubber acrylonitrile-isoprene rubber, isoprenerubber, polyglycol ether, vinylpyridine-butadiene rubber, polyethylene,and methyl silicone rubber with phenyl groups.

[0084] Fillers may also include polyfluoralkoxyphosphazene,polynorbornene, propyleneoxide rubber, polypropylene,vinylpyridine-styrene-butadiene rubber, urethane rubbers, methylsilicone rubber with phenyl and vinyl groups, styrene-butadiene rubber,styrene-butadiene-styrene block copolymer (thermoplastic elastomer),styrene-chloroprene rubber, polysiloxane treated EPDM, styrene-isoprenerubber, styrene-isoprene-styrene block copolymer (thermoplasticelastomer), polythioglycol ether, tetrafluoroethylene, polysulfiderubbers, trans-polyoctenamer, trans-polypentenamer, thermoplasticelastomers, thermoplastic polyolefins, thermoplastic polyurethanes,methyl silicone rubber with vinyl groups, crosslinkable polyethylene,emulsion polymer, solution polymer, oil-extended rubber,poly(vinylchloride-co-vinyl acetate-co acrylic acid),poly(ethylene-co-vinylacetate-co-acrylic acid).

[0085] Fillers may also include blowing agents such as azo compoundslike diazoaminobenzene, azobisisobutyronitrile, azodicarbonamide,azodicarbonic acid, benzene sulfonyl hydrazide,benzene-1,3-disulfonylhydrazide, diphenyloxide-4,4′-disulfonylhydrazide,p-toluenesulfonic acid hydrazide, N,N′dinitrosopentamethylenetetraamine,N,N-dimethyl-N,N′-dinitrosophthalamide, and sodium carbonate blends withacidic compounds such as tartaric acid.

[0086] In a preferred embodiment, the curable resin compositioncomprises about 30 to about 70 parts of an unsaturated polyester; about15 to about 50 parts of an alkenyl aromatic monomer; and about 0.1 toabout 12 parts of a capped poly(arylene ether); wherein all amounts arebased on 100 parts resin.

[0087] In a highly preferred embodiment, the composition comprises about30 to about 70 parts of an unsaturated polyester; about 15 to about 50parts styrene; about 1 to about 8 parts of a capped poly(arylene ether)having an intrinsic viscosity of about 0.10 to about 0.35 dL/g; about0.1 to about 4 parts of a curing catalyst; and about 0.01 to about 1parts of a curing promoter; wherein all amounts are based on 100 partsresin.

[0088] It will be understood that the invention includes uncured,partially cured, and fully cured compositions.

[0089] There is no particular limitation on the methods by which thecurable resins are processed. Suitable methods include, for example,hand lay-up and spray lay-up, casting, sheet molding, bulk molding,injection molding, pultrusion, vacuum impregnation, and the like.

[0090] There is no particular limitation on the method by which thecomposition may be cured. The composition may, for example, be curedthermally or by using irradiation techniques, including UV irradiationand electron beam irradiation.

[0091] In a preferred embodiment, the composition is suitable forlow-temperature curing. For example, the composition may be cured underconditions comprising a curing temperature not greater than about 50° C.(preferably not greater than about 40° C., more preferably not greaterthan about 30° C.) and a curing time not greater than about 5 hours(preferably not greater than about 1 hour, more preferably not greaterthan about 30 min). A cured composition will preferably exhibit a Barcolsurface hardness measured according to ASTM D2583 of at least about 30,more preferably at least about 40.

[0092] The invention is further illustrated by the followingnon-limiting examples.

EXAMPLES 1-6, COMPARATIVE EXAMPLES 1-6

[0093] The unsaturated polyester resin system used in these examples wasthe proprietary resin obtained from Ashland as Q6585. It is described byits manufacturer as “high-reactivity, thickenable, polyester resin foruse in low profile and controlled shrink applications.” The datasheetsupplied with the material indicates a styrene content of 35 weightpercent. In Examples 1-6, the LPA was a capped poly(arylene ether).Specifically, the capped poly(arylene ether)s were methacrylate-cappedpoly(2,6-dimethylphenyl ether)s (PPE-MAA) having intrinsic viscositiesof 0.12 and 0.31 dl/g as measured in chloroform at 23° C. The cappedpoly(arylene ether)s were prepared by reaction of the correspondinguncapped polyarylene ethers with methacrylic anhydride, using proceduresdescribed in U.S. patent application Ser. No. 09/440,747, filed Nov. 16,1999. A commercial LPA containing a polyvinyl acetate, obtained asLP-40A from Union Carbide, was used as comparison. The initiator packagewas mixture of the curing catalyst methylethyl ketone peroxide (MEKP)and the curing promoter cobalt ethylhexanote.

[0094] The compounding was conducted as follows. Styrene was weighedinto a disposable beaker and to this was added the LPA. In the case ofPPE-MAA, the mixture was then heated briefly (less than 10 minutes) on awater bath at about 60° C. with hand mixing until complete dissolutionwas achieved. To this mixture was then added the Q6585 resin. Once mixedthoroughly, the curing catalyst, MEKP, was added using a calibratedsyringe. When the resulting mixture was sufficiently mixed, the curingpromoter was then added, again using a calibrated syringe. Theindividual mixtures were then poured into molds and placed in an airconvection oven set at 35° C.

[0095] The onset of gelling occurred within the range of one half to twohours, each with a substantial exotherm, after which the parts appearedhard and cured. Generally, samples containing the PPE-MAA cured in shorttimes, and those without PPE-MAA took longer. The molds were then takenfrom the oven and allowed to cool to ambient conditions. The sampleswere allowed to sit for 24 hours before their final length was measured.The percent shrinkage was calculated by comparing the initial length tothe final length, where the initial length is the length of the mold,and the final length is the length of the molded bar after curing and 24hours at ambient conditions.

[0096] The results are presented in Table 1 and show that thecompositions of Examples 1-6, with a capped poly(arylene ether), exhibitreduced shrinkage compared to compositions with polyvinyl acetate andthose with no LPA. As shown in FIG. 1, compositions of the inventionalso exhibit reduced brittleness. In particular, the sample labeled #2(“UPR+4% Unsat.-PPE”), corresponding to Example 1 of Table 1, isuncracked, whereas the samples labeled #1 (“UPR+4% PVA”) and #3 (“UPRneat”), corresponding to Comparative Examples 1 and 2, respectively, ofTable 1, exhibit multiple cracks and fractures. TABLE 1 C. Ex. 1 C. Ex.2 C. Ex. 3 C. Ex. 4 C. Ex. 5 C. Ex. 6 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex.6 LPA TYPE none none none PVA PVA PVA PPE.12 PPE.12* PPE.12 PPE.31PPE.31** PPE.31 LPA LEVEL 0.00% 0.00% 0.00% 2.00% 4.00% 6.00% 2.00%4.00% 6.00% 2.00% 4.00% 6.00% BATCH SIZE (g) 130.00 130.00 130.00 130.00130.00 130.00 130.00 130.00 130.00 130.00 130.00 130.00 Styrene (g)15.60 15.60 15.60 15.60 15.60 15.60 15.60 15.60 15.60 15.60 15.60 15.60LPA (g) 0.00 0.00 0.00 2.60 5.20 7.80 2.60 5.20 7.80 2.60 5.20 7.80Resin (g) 112.97 112.97 112.97 110.37 107.77 105.17 110.37 107.77 105.17110.37 107.77 105.17 curing catalyst (mL; 1.16 1.16 1.16 1.16 1.16 1.161.16 1.16 1.16 1.16 1.16 1.16 d = 1.1200; 1.00 wt %) curing promotor(mL; 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 d =0.8874; 0.10 wt %) Initial length (mm) 254.00 254.00 254.00 254.00254.00 254.00 254.00 254.00 254.00 254.00 254.00 254.00 Final length(mm) 245.50 245.50 245.50 244.50 246.00 248.00 248.00 249.00 249.00248.00 248.00 249.00 Curing Shrinkage (%) 3.3 3.3 3.3 3.7 3.1 2.4 2.42.0 2.0 2.4 2.4 2.0

EXAMPLE 7, COMPARATIVE EXAMPLES 7-10

[0097] Using the procedures described above, seven samples containingthe unsaturated polyester resin Ashland Q6585 were prepared withvariations in poly(arylene ether) capping (none or methacrylate cap),intrinsic viscosity (0.12, 0.25, or 0.31 dL/g), and amount. All sampleswere cured for 16 hours at 35° C. The results are presented in Table 2and show that Example 8, with a methacrylate-capped poly(arylene ether),cured more rapidly than compositions with uncapped poly(arylene ether)sor with no LPA. TABLE 2 C. Ex. 7 C. Ex. 8 C. Ex. 9 C. Ex. 10 Ex. 7 LPATYPE none PPE PPE PPE PPE LPA LEVEL 0.00% 5.00% 5.00% 5.00% 5.00%poly(arylene ether) intrinsic NA 0.12 0.31 0.25 0.12 viscosity (dL/g)poly(arylene ether) cap — none none none MA* BATCH SIZE (g) 35.5 35.535.5 35.5 35.5 styrene (g) 1.78 1.78 3.55 3.55 1.78 poly(arylene ether)(g 0.00 1.78 1.78 1.78 1.78 Resin (g) 33.33 31.56 29.78 29.78 31.56 MEKP(mL; d = 1.1200) 0.32 0.32 0.32 0.32 0.32 curing promoter (mL; d =0.8874) 0.040 0.040 0.040 0.040 0.040 Condition after 16 hrs Gelled,Liquid Liquid, Liquid, Hardened Not cured inhomogen inhomogen

EXAMPLES 8-13, COMPARATIVE EXAMPLE 11

[0098] Seven samples were prepared with variations in cappedpoly(arylene ether) intrinsic viscosity and amount. The unsaturatedpolyester resin (UPR) used in these samples was a proprietary resinobtained from Alpha Owens Corning as AOC XV2346, which is described byits manufacturer as containing 40-60% styrene and 40-60% solids. Thecapped poly(arylene ether)s were methacrylate-cappedpoly(2,6-dimethylphenyl ether)s having intrinsic viscosities of 0.12 and0.31 dL/g, prepared according to the procedure referenced above. For allsamples, the curing promoter was cobalt naphthanate. All samples werecured for about 24 24 hours at 25° C. The compositions and curingshrinkage results are presented in Table 3. The results indicate that amoderate amount (2% or 4%) of either capped poly(arylene ether) reducedcuring shrinkage, while higher amounts caused expansion. FIG. 2 showsimages of four of the molded compositions comprising capped poly(aryleneether) having an intrinsic viscosity of 0.12 dL/g, sample labels in thefigure corresponding to example numbers as follows: 1=C. Ex. 11; 2=Ex.8; 3=Ex. 9; 4=Ex. 10. The figure shows that the sample labeled (1),corresponding to C. Ex. 11 with no added capped poly(arylene ether),exhibited shrinkage, whereas the sample labeled (2), corresponding toEx. 8 with 2 weight percent methacrylate-capped poly(arylene ether)having an intrinsic viscosity of 0.12 dL/g, exhibited reduced shrinkage;Exs. 9 and 10, with 4 weight percent and 6 weight percentmethacrylate-capped poly(arylene ether), respectively, exhibitedexpansion. TABLE 3 C. Ex. 11 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13Resin type UPR UPR UPR UPR UPR UPR UPR Poly(arylene ether) intrinsicviscosity (dL/g) — 0.12 0.12 0.12 0.31 0.31 0.31 Poly(arylene ether)amount (weight percent) 0.00 2.00 4.00 6.00 2.00 4.00 6.00 Batch size(g) 142.00 142.00 142.00 142.00 142.00 142.00 142.00 Styrene (g) 17.0417.04 17.04 17.04 17.04 17.04 17.04 Poly(arylene ether) (g) 0.00 2.845.68 8.52 2.84 5.68 8.52 Resin amount (g) 122.48 119.64 116.80 113.96119.64 116.80 113.96 Curing Promoter (ml; d = 0.8874 g/ml; 0.40 0.400.40 0.40 0.40 0.40 0.40 0.25 wt %) DMA (mL; d = 0.9560 g/mL; 0.20 wt %)0.30 0.30 0.30 0.30 0.30 0.30 0.30 MEKP (mL; d = 1.1200 g/mL; 1.50 wt %)1.90 1.90 1.90 1.90 1.90 1.90 1.90 Cure Temperature (° C.) 25 25 25 2525 25 25 Volume Change (%) −0.4 −0.6 * * −0.7 +1.8 +3.5

EXAMPLES 14-21

[0099] The components used for Examples 8-13 and Comparative Example12-11 were used to study the effect of curing catalyst and curingpromoter amount.

[0100] Compositions, curing conditions, and shrinkage results for eightcompositions are presented in Table 4. The results show that the cappedpoly(arylene ether)s provide faster curing that can be used to reducethe amount of curing catalyst and curing promoter at a given curingtime.

[0101] Images of the eight molded parts, after curing, are provided inFIG. 3. The parts correspond, left to right, to Examples 14-21 in Table4. TABLE 4 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21 ResinType UPR UPR UPR UPR UPR UPR UPR UPR capped poly(arylene ether)intrinsic viscosity 0.12 0.31 0.12 0.31 0.12 0.31 0.12 0.31 (dL/g)capped poly(arylene ether) amount (wt %) 4.00 4.00 4.00 4.00 4.00 4.004.00 4.00 Batch Size (g) 142.00 142.00 142.00 142.00 142.00 142.00142.00 142.00 Styrene amount (g) 17.04 17.04 17.04 17.04 17.04 17.0417.04 17.04 capped poly(arylene ether) amount (g) 5.68 5.68 5.68 5.685.68 5.68 5.68 5.68 Resin amount (g) 118.04 118.04 117.79 117.79 117.54117.54 117.29 117.29 Curing Promoter amount (mL; d = 0.8874 g/cc; 0.200.20 0.24 0.24 0.28 0.28 0.32 0.32 0.25 wt %) DMA (mL; d = 0.9560 g/cc;0.20 wt %) 0.15 0.15 0.18 0.18 0.21 0.21 0.24 0.24 MEKP (mL; d = 1.1200g/cc; 1.50 wt %) 0.95 0.95 1.14 1.14 1.33 1.33 1.52 1.52 Cure PackageLevel 50% 50% 60% 60% 70% 70% 80% 80% Cure Temperature (° C.) 25 25 2525 25 25 25 25 Cure Time (hours and minutes) 4 h 5 m >5 h 2 h 25 m 2 h25 m 1 h 45 m >5 h 1 h 15 m 1 h 15 m Initial length (mm) 254.0 254.0254.0 254.0 254.0 254.0 254.0 254.0 Final length (mm) 252.0 * 253.0253.5 253.0 * ** ** Volume Change (%) −0.8 — −0.4 −0.2 −0.4 — — —

[0102] While the invention has been described with reference topreferred embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing fromessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

[0103] All cited patents and other references are incorporated herein byreference in their entirety.

claims:
 1. A curable resin composition, comprising: an unsaturatedpolyester; an alkenyl aromatic monomer; and an amount of a cappedpoly(arylene ether) effective to reduce curing shrinkage.
 2. The curableresin composition of claim 1, wherein the unsaturated polyester is thereaction product of at least one polyhydric alcohol with at least onepolybasic acid comprising an unsaturated polybasic acid.
 3. The curableresin composition of claim 2, wherein the unsaturated polybasic acid isselected from the group consisting of maleic acid, fumaric acid,itaconic acid, citraconic acid, chloromaleic acid, dimeric methacrylicacid, nadic acid, tetrahydrophthalic acid,endo-methylenetetrahydrophthalic acid,hexachloro-endo-methylenetetrahydrophthalic acid, halogenated phthalicacids, the corresponding esters and anhydrides of the foregoingunsaturated polybasic acids, and mixtures comprising at least one of theforegoing unsaturated polybasic acids, esters, and anhydrides.
 4. Thecurable resin composition of claim 2, wherein the polyhydric alcohol isselected from the group consisting of ethylene glycol, propylene glycol,diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol,1,4-butanediol, neopentyl glycol, glycerol, triethylene glycol,pentanediol, hexylene glycol, hydrogenated bisphenol A, bisphenolA-alkylene oxide adducts, tetrabromobisphenol A-alkylene oxide adducts,and mixtures comprising at least one of the foregoing polyhydricalcohols.
 5. The curable resin composition of claim 2, wherein thepolybasic acid further comprises a saturated or aromatic polybasic acidselected from the group consisting of succinic acid, adipic acid,sebacic acid, azelaic acid, dodecanedioic acid, eicoic acid, phthalicacid, isophthalic acid, terephthalic acid, the corresponding esters andanhydrides of the foregoing polybasic acids, and mixtures comprising atleast one of the foregoing saturated or aromatic polybasic acids,esters, and anhydrides.
 6. The curable resin composition of claim 1,wherein the unsaturated polyester is the reaction product of at leastone polyhydric alcohol comprising propylene glycol; at least oneunsaturated polybasic acid comprising maleic acid or maleic anhydride;and at least one aromatic polybasic acid comprising phthalic acid,phthalic anhydride, or isophthalic acid.
 7. The curable resincomposition of claim 1, comprising about 20 to about 80 parts of theunsaturated polyester per 100 parts resin.
 8. The composition of claim1, wherein the alkenyl aromatic monomer has the structure

wherein each R¹ is independently selected from the group consisting ofhydrogen and C₁-C₁₂ alkyl; each R² is independently selected from thegroup consisting of halogen, C₁-C₁₂ alkyl, and C₁-C₁₂ alkoxyl; X isnitrogen or carbon; p is 1 to 4; and q is 0 to
 5. 9. The composition ofclaim 1, wherein the alkenyl aromatic monomer is selected from the groupconsisting of styrene, alpha-methylstyrene, 2-methylstyrene,3-methylstyrene, 4-methylstyrene, 2-t-butylstyrene, 3-t-butylstyrene,4-t-butylstyrene, 1,3-divinylbenzene, 1,4-divinylbenzene,1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, styrenes having from1 to 5 halogen substituents on the aromatic ring, vinylpyridine,2,4-divinylpyridine, 2,5-divinylpyridine, 2,6-divinylpyridine,3,5-divinylpyridine, 2,4,6-trivinylpyridine, and mixtures comprising atleast one of the foregoing alkenyl aromatic monomers.
 10. The curableresin composition of claim 1, comprising about 10 to about 70 parts ofthe alkenyl aromatic monomer, based on 100 parts resin.
 11. The curableresin composition of claim 1, wherein the capped poly(arylene ether) hasthe structure Q—(J—K)_(y) wherein Q is the residuum of a monohydric,dihydric, or polyhydric phenol; y is 1 to 100; J comprises recurringunits having the structure

wherein R³-R⁶ are each independently selected from the group consistingof hydrogen, halogen, primary or secondary C₁-C₁₂ alkyl, C₁-C₁₂ alkenyl,C₁-C₁₂ alkynyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂ hydroxyalkyl, phenyl, C₁-C₁₂haloalkyl, C₁-C₁₂ aminoalkyl, C₁-C₁₂ hydrocarbonoxy, and C₁-C₁₂halohydrocarbonoxy, wherein at least two carbon atoms separate thehalogen and oxygen atoms; m is 1 to about 200; and K is a capping groupselected from the group consisting of

wherein R⁷ is C₁-C₁₂ alkyl; R⁸-R¹⁰ are each independently selected fromthe group consisting of hydrogen, C₁-C₁₂ alkyl, C₁-C₁₂ alkenyl, C₁-C₁₂aryl, C₁-C₁₂ mixed (alkyl-aryl), C₁-C₁₂ alkoxycarbonyl, C₁-C₁₂aryloxycarbonyl, mixed (alkyl-aryl)oxycarbonyl, nitrile, formyl,carboxylate, imidate, and thiocarboxylate; R¹¹-R¹⁵ are eachindependently selected from the group consisting of hydrogen, halogen,C₁-C₁₂ alkyl, hydroxy, and amino; and wherein Y is a divalent groupselected from the group consisting of

wherein R¹⁶ and R¹⁷ are each independently selected from the groupconsisting of hydrogen and C₁-C₁₂ alkyl.
 12. The curable resincomposition of claim 11, wherein Q is the residuum of a monohydricphenol.
 13. The curable resin composition of claim 1, wherein the cappedpoly(arylene ether) comprises a capping group having the structure

wherein R⁸-R¹⁰ are each independently selected from the group consistingof hydrogen, C₁-C₁₂ alkyl, C₁-C₁₂ alkenyl, C₁-C₁₂ aryl, C₁-C₁₂ mixed(alkyl-aryl), C₁-C₁₂ alkoxycarbonyl, C₁-C₁₂ aryloxycarbonyl, mixed(alkyl-aryl)oxycarbonyl, nitrile, formyl, carboxylate, imidate, andthiocarboxylate.
 14. The curable resin composition of claim 1, whereinthe capped poly(arylene ether) has an intrinsic viscosity of about 0.08to about 0.40 deciliters per gram, as measured in chloroform at 23° C.15. The curable resin composition of claim 1, wherein the cappedpoly(arylene ether) is substantially free of amino substituents.
 16. Thecurable resin composition of claim 1, comprising about 0.1 to about 12parts of the capped poly(arylene ether) per 100 parts resin.
 17. Thecurable resin composition of claim 1, further comprising a curingcatalyst.
 18. The curable resin composition of claim 17, comprising notgreater than about 1.5 parts of the curing catalyst per 100 parts resin.19. The curable resin composition of claim 1, further comprising acuring promoter.
 20. The curable resin composition of claim 19,comprising not greater than about 0.2 parts of the curing promoter per100 parts resin.
 21. The curable resin composition of claim 16, whereinthe curing catalyst is selected from the group consisting of benzoylperoxide, dicumyl peroxide, methyl ethyl ketone peroxide, laurylperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl benzenehydroperoxide, t-butyl peroctoate,2,5-dimethylhexane-2,5-dihydroperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)-hex-3-yne, di-t-butylperoxide,t-butylcumyl peroxide,alpha,alpha′-bis(t-butylperoxy-m-isopropyl)benzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumylperoxide,di(t-butylperoxy isophthalate, t-butylperoxybenzoate,2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide,trimethylsilylphenyltriphenylsilyl peroxide,2,3-dimethyl-2,3-diphenylbutane,2,3-trimethylsilyloxy-2,3-diphenylbutane, and mixtures comprising atleast one of the foregoing curing catalysts.
 22. The curable resincomposition of claim 1, further comprising at least one curing promoter.23. The curable resin composition of claim 1, wherein the curingpromoter is selected from the group consisting of cobalt naphthanate,cobalt ethylhexanoate, N,N-dimethylaniline, N,N-diethylaniline, andmixtures comprising at least one of the foregoing curing promoters. 24.The curable resin composition of claim 1, further comprising at leastone additive selected from the group consisting of flame retardants,flame retardant synergists, mold release agents and other lubricants,antioxidants, thermal stabilizers, ultraviolet stabilizers, pigments,dyes, colorants, anti-static agents, fibrous reinforcements, disc-shapedfillers, low-aspect ratio fillers, synthetic resins, natural resins, andthermoplastic elastomers.
 25. The curable resin composition of claim 1,wherein the amount of the capped poly(arylene ether) is effective toreduce the curing shrinkage in any one dimension by at least about 25%compared to the shrinkage of a corresponding composition without thecapped poly(arylene ether).
 26. The curable resin composition of claim1, exhibiting a curing shrinkage in any one dimension not greater thanabout 3.0%; wherein curing shrinkage is defined by the equation$S = {100( \frac{L_{before} - L_{after}}{L_{before}} )}$

wherein S is the curing shrinkage expressed as a percent, L_(before) isthe length before curing of a molded object comprising the composition,and L_(after) is the length after curing of a molded object comprisingthe composition.
 27. The curable resin composition of claim 1, whereinthe composition is curable under conditions comprising a curingtemperature not greater than about 50° C. and a curing time not greaterthan about 30 hours.
 28. A curable resin composition, comprising: about30 to about 70 parts of an unsaturated polyester; about 15 to about 50parts of an alkenyl aromatic monomer; and about 0.1 to about 12 parts ofa capped poly(arylene ether); wherein all amounts are based on 100 partsresin.
 29. A curable resin composition, comprising: about 30 to about 70parts of an unsaturated polyester; about 15 to about 50 parts styrene;about 1 to about 8 parts of a capped poly(arylene ether) having anintrinsic viscosity of about 0.10 to about 0.35 dL/g; about 0.1 to about2.5 parts of a curing catalyst; and about 0.01 to about 1 parts of acuring promoter; wherein all amounts are based on 100 parts resin.
 30. Acurable resin composition, comprising the reaction product of: anunsaturated polyester; an alkenyl aromatic compound; and an amount of acapped poly(arylene ether) effective to reduce the volume change thataccompanies curing.
 31. An article comprising the composition of claim27.
 32. An automotive part comprising the composition of claim
 27. 33. Amethod of preparing a curable resin composition, comprising: blending analkenyl aromatic compound and a capped poly(arylene ether) to form afirst blend; and blending the first blend and an unsaturated polyesterto form a second blend.
 34. A method of preparing a cured resincomposition, comprising: blending an alkenyl aromatic compound and acapped poly(arylene ether) to form a first blend; blending the firstblend and an unsaturated polyester to form a second blend; and curingthe second blend at a temperature not greater than about 50° C. for atime not greater than about 30 hours.